Have any of you ever had scale growing in the folds of the leaves? The ants have moved in and are 'farming' the scale similar to what they do for aphids. They go for the honeydew excreted by the scale. The ants have established colonies among the iris plants.

In other plants you scrape them off, wash with soapy water and sometimes use an insecticide. I have not dug them up yet, but apparently scale can infect the roots too. I've never heard anyone talk about getting scale on their irises.

If you have any experience or advice on the best way to treat this infestation I would love to learn from your experience! I discovered them as it was getting dark. Tomorrow I will investigate further.

Scales tend to be a small problem with most irises, but once established they will overtake the area/plant. Ants do not destroy them. Only when in their "soft" stage do any liquid sprays work to kill them. When in their hard shell stage they are impervious to the sprays. The danger of the sprays is that predatory wasps and ladybugs, which can destroy the scale, are also killed.

Recommendation from http://www.herbs2000.com/flowers/i_pests_dis.htm is to destroy the plant infested with heavy amount of scale. At this stage of the season I would just cut off the affected foliage and put it in the trash, then watch the plant carefully. If only a small amount the scale can be manually crushed or swabbed with a cotton swab dipped in alcohol.

Dave, thanks for the excellent link. It confirmed what I already knew about scale...but with reference to irises. The infested area only has about 40 plants. I don't want to use insecticide, both to protect the beneficial insects and to protect the birds that eat the insects. I'm going to remove the infested leaves and try wiping with alcohol. I know controlling ants is important too so I'll have to research what is the best way to reduce the ant population. When I get out there in a little while I'll take pictures and dig up a few to make sure the roots aren't infested. I really don't want to destroy that many plants!!!!

That is a very interesting link ! Thanks for sharing it, Dave ! I can't say I've ever had this problem, but maybe a closer inspection is called for . My "ant problem" is a little different...the darn things want to make their "hills" at the base of the plant....and then the iris is "too deep"in the ground .

Ok...I completed the first stage of treatment. I have removed the infested leaves and squished any visible scale. All the leaves went immediately into the covered trash can. Of course I may have missed some of the scale because the they crawl into the folds between the leaves and are hidden. If they have been there awhile the signs are obvious. But if they are new larvae I might have missed them, so I will have to keep a close eye on my plants.

I decided I prefer not to use alcohol for several reasons. First I don't have that much on hand, secondly I don't want to expose myself to that much alcohol. It is absorbed through the skin (and is in most personal care products) and is suspected of being related to immune problems, cancers and parasite infestation.

I plan to try spraying dilute dish soap on the plants...knowing that it won't get into the crevices between leaves...but it may help clean up any exposed eggs, larvae, or adults that I missed when removing the outer leaves.

Here is what I found after pulling off the outer leaves that were hiding the scale and their damage:

Note there are scale insects, white debris, soil, and (not visible in the pictures) the leaves are sticky from the clear honeydew that the scale emit. The honeydew is what the ants eat. Ants will actually protect the scale from being eaten by beneficial insects, which is why it is said that ants 'farm' these insects. This is why it is important to control the ants.

The last photo shows a little of the black sooty mold that is a classic symptom of having an infestation of insects that make honeydew (mainly aphids and scale).

I was leaning toward treating them every few days...watching, cleaning, etc. At least for a first step. I still need to dig up a few of the worst ones and see if the scales have infested the roots. I don't want to dig them all up unless other treatments don't work. If I dig them up them I'm pretty much sacrificing any chance of a spring bloom. I don't have any new place to move them to that is prepared...so that's not an option right now either...although in a pinch there is an area I can clean up relatively quickly.

I am fortunate that the weather is nice and my ground will not freeze so I have a little time to work with while I treat and observe the progress. Usually scale is a minor problem...and relatively easy to treat so I'm going to take it step by step rather than taking drastic measures. I consider this a learning experience. I don't think the plants are at risk of being killed as long as I watch them closely and stay on top of it.

I guess we will see.....I'll keep you posted. Lunch break is over now, time to get back out there!

Glad I can contribute! I have certainly learned a lot from all of the rest of you! Since I have to deal with it anyway I might as well share...and by sharing I get the benefit of everyone's helpful suggestions and links (thanks again Dave ).

Time for another refill! The good news is that it doesn't look like the scale are attacking the roots. I did discover some hiding around the base of the plant where the foliage was touching the ground, so I am moving the dirt away as I work and drenching the base of the plants thoroughly.

I have removed the mature leaves and left primarily the small tightly connected young leaves. I have not observed any scale between the young leaves so I think this will be ok and leave the plants with enough greenery to continue photosynthesis and growth (this is one of my two peak growing seasons... when the weather cools down in fall, and when it warms up in spring). If I completely defoliate the plants I am concerned that they will be stunted...which I would like to avoid if I can!

It has been interesting to observe that certain plants are more susceptible than others...and it may be something to do with the chemistry/flavor of the fluids in the plant that the scale suck...but actually I am beginning to suspect it has more to do with the shape and tightness of the connection between the separate leaves in the fan. There are some plants that seem to be too tight for the scale to thrive, and some that are so open and loose that the scale don't seem to like them. It's the 'in-betweeners" where I seem to be finding the thriving communities of scales!

If you use rubber gloves, the alcohol shouldn't bother you. Once upon a time My great grandmother's (went to heaven in the 30's or 40's) jade plant had all kinds of scales. I wiped them off with alcohol, one at a time. My aunt still has the plant.

Dunno if that would be practical for so many plants. What about neem oil?